Title : RECENT RESEARCH ON THE DETERMINATION OF NATURAL MODES AND FREQUENCIES OF AIRCRAFT WING STRUCTURES,

Corporate Author : ADVISORY GROUP FOR AERONAUTICAL RESEARCH AND DEVELOPMENT PARIS (FRANCE)

Personal Author(s) : Hedgepeth, John M.

Report Date : APR 1956

Pagination or Media Count : 24

Abstract : The results of some theoretical and experimental studies of the vibrations of aircraft wing structures are summarized and discussed. Assessment is made of the importance of various effects not usually included in the elementary theories of bending and torsion of box beams, such as transverse shear flexibility, shear lag, restraint of warping, longitudinal (rotary) inertia, and cross-sectional deformability. The substitute stringer method of incorporating the effects of shear lag into the analysis of box-beam vibration is outlined. Natural frequencies obtained experimentally from resonance tests of box-beam specimens are presented and compared with the results of theoretical calculations, and it is shown that good agreement, particularly for the higher modes, requires the inclusion of secondary effects in the analysis. Two recently developed methods of analysis of low-aspect-ratio wings are described. Frequencies and modes calculated by these two methods are compared with those obtained experimentally for a large-scale builtup delta-wing specimen. (Author)